Galvalume coil uses the cold-rolled steel sheet as a substrate and solidified by 55% aluminum, 43.5% zinc and 1.5% silicon at 600 °C. It combines the physical protection and high durability of aluminum and the electrochemical protection of zinc. Giving it strong corrosion resistance, 3 times that of galvanized steel sheet. The density of 55% aluminum is smaller than the density of zinc.